Cortisol
Label Mnemonic: CORT
Epic Lab Code: LAB61
Downtime Form: A-1a General Laboratory Requisition
Chemistry
6240 RCP
356-3527
Specimen(s):
Plasma
Specimen Instructions:
Specify collection time.
Collection Medium:
Plasma Separator Tube 4.5 mL
Alternate Collection Media:
Call laboratory for additional acceptable specimen collection containers.
Minimum:
3 mL whole blood from light green top tube or TWO Microtainer® devices
Testing Schedule:
24 hrs/day, 7 days a week, including holidays.
Turn Around Time:
1 hour (upon receipt in laboratory)
Reference Range:
AM (6-10) 6.0-18.4 μg/dL PM (4-8) 2.7-10.5 μg/dL Significant value: <2.0 μg/dL Assay version updated to Roche Diagnostics Cortisol II assay, along with updated reference ranges, on 2/7/2017.
Test Limitations:
The assay is unaffected by icterus (bilirubin is less than 25 ng/dL), (hemolysis index is less than 500), lipemia (Intralipid is less than 1500 mg/dL) and biotin is less than 30 ng/mL (criterion: recovery within plus or minus 10% of initial value).

In patients receiving therapy with high biotin doses (i.e. is greater than 5 mg/day) no sample should be taken until at least 8 hours after the last biotin administration.

No interference was observed from rheumatoid factor (up to 600 U/mL).

In vitro tests were performed on 16 commonly used pharmaceuticals. No interference with the assay was found.

In rare cases, interference due to extremely high titers of antibodies to analyte-specific antibodies, streptavidin and ruthenium can occur. These effects are minimized by suitable test design.

Pregnancy, contraceptives and estrogen therapy give rise to elevated cortisol concentrations.

The cortisol assay has no cross-reactivity with dexamethasone and low cross-reactivity with prednisone, prednisolone, and 6-methylprednisolone. Patients treated with prednisone, prednisolone, and 6-methylprednisolone (especially higher doses) may show falsely elevated concentrations of cortisol. Patients with 21-hydroxylase deficiency may have elevated 21-deoxycortisol levels that can give rise to falsely elevated cortisol results.

The time of sample collection must be taken into account when interpreting results due to the cortisol secretion circadian rhythm. Severe stress can also give rise to elevated cortisol levels. For diagnostic purposes, the Cortisol results should always be assessed in conjunction with the patient's medical history, clinical examination and other findings.
Methodology:
Electrochemiluminescence Immunoassay
CPT Code:
82533
 
See Additional Information:
Chemistry Critical Lab Values